diff --git a/src/ui/sand_box.c b/src/ui/sand_box.c
index 2be5ad3..5fbec6f 100644
--- a/src/ui/sand_box.c
+++ b/src/ui/sand_box.c
@@ -40,7 +40,7 @@ void on_activate_window_creation (GtkApplication *app, gpointer data)
     gtk_window_set_child (GTK_WINDOW (that_window), my_scrolling_thing);
     gtk_widget_show (that_window);
     and_now_let_s_climb_that_tree (my_scrolling_thing);
-    if (data) {g_print (data);  g_print (" and is displayed by [sand_box.c / on_activate_window_creation()]\n");}
+    if (data) {g_print (data);  g_print (" and is displayed by : sand_box.c / on_activate_window_creation()\n");}
 }
 //-------------------------------------------------------------------------------------------------------------------------------------------
 
@@ -75,14 +75,16 @@ static void on_selection_change (GtkStringList *my_selection_model,  guint posit
 //-------------------------------------------------------------------------------------------------------------------------------------------
 
 void on_activating_this_expander (GtkExpander *my_expander, gpointer my_data) {
-    printf("on_activating exp.  >   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(my_expander)));}
+    //printf("on_activating exp.  >   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(my_expander)));
+}
 void gtk_expander_set_child      (GtkExpander* expander, GtkWidget* child) {
-    printf("gtk_expander_set_child ()   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(child)));}
+    //printf("gtk_expander_set_child ()   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(child)));
+}
 
 GListModel *my_item_create_func (gpointer item, gpointer user_data)
 {
     printf("%s   ", gtk_string_object_get_string(item));
-    gchar *my_child_array[] = {"1", "2", "3", NULL};
+    gchar *my_child_array[] = {"10", "2", "3", NULL};
     GtkStringList *my_child_string_list = gtk_string_list_new ((const char * const *) my_child_array);
 
     if (strcmp(gtk_string_object_get_string(item), "zero")) {
@@ -113,7 +115,7 @@ static void and_now_let_s_climb_that_tree (GtkWidget *in_that_box)
 //  https://docs.gtk.org/gtk4/callback.TreeListModelCreateModelFunc.html
 //  https://docs.gtk.org/gtk4/method.TreeListRow.set_expanded.html
 
-    GtkTreeListModel *my_tree_list_model = gtk_tree_list_model_new (G_LIST_MODEL (my_string_list), 1, 0, my_item_create_func, NULL, NULL);
+    GtkTreeListModel *my_tree_list_model = gtk_tree_list_model_new (G_LIST_MODEL (my_string_list), 1, 1, my_item_create_func, NULL, NULL);
     int rank = 1; printf("in : GListModel *item_create_func (gpointer item,...)   (line 80)     (item n°%d is %s)\n",
                       rank, gtk_string_list_get_string (my_string_list, rank));